Background. The role of antiretroviral treatment for adults in the pubic sector in South Africa is debated with little consideration of programme choices that could impact on the cost-effectiveness of the intervention. This study seeks to explore the impact of these programme choices at an individual level, as well as explore the total cost of a rationed national public sector antiretroviral treatment programme.

Methods. Eight Scenarios were modelled of limited national treatment programmes over the next 5 years, reflecting different programme design choices. The individual costeffectiveness of these scenarios were compared. The total costs of the most cost-effective scenario were calculated, and the potential for savings in other areas of health care utilisation was explored.

Results. The direct programme costs per life-year saved varied between scenarios from R5 923 to R11 829. All the costs of the most cost-effective scenario could potentially be offset depending on assumptions of health care access and utilisation. The total programme costs for the most costeffective scenario in 2007 with 107 000 people on treatment are around R409 million.

Conclusion. Specific policy choices could almost double the number of people who could benefit from an investment in a limited national antiretroviral treatment programme. Such a programme is affordable within current resource constraints. The consideration of antiretroviral treatment calls for a unique public health approach to the rationing of health services in the public sector.